Vitamin D and Eye Health
Vitamin D receptors are present in the retina, corneal epithelium, and lacrimal gland. Deficiency associations exist for several eye conditions; supplementation evidence is generally strongest for dry eye and weakest for AMD.
Age-related macular degeneration (AMD)
Meta-analyses find lower 25(OH)D is associated with higher AMD prevalence, but the AREDS2 supplementation trial did not test vitamin D directly. The Carotenoids in Age-Related Eye Disease Study (CAREDS) found women with 25(OH)D < 12 ng/mL had a 6.7-fold higher risk of early AMD than women with sufficient vitamin D. No randomised trial has yet proven supplementation slows AMD progression — that evidence is still awaited.
Dry eye disease
Multiple RCTs (Bae 2016; Yildirim 2016) reported vitamin D repletion improved tear film stability, Schirmer score, and OSDI symptom scores in patients with dry eye and baseline deficiency. Vitamin D modulates lacrimal gland inflammation and goblet cell function. Reasonable adjunct to artificial tears, warm compresses, and (in refractory cases) cyclosporine or lifitegrast eye drops.
Myopia in children
Time spent outdoors is one of the most consistent factors linked to reduced myopia progression in children — but the mechanism appears to be light intensity on the retina (driving dopamine release), not vitamin D per se. Mendelian randomisation studies suggest 25(OH)D is not causally related to myopia. The outdoor recommendation stands; the vitamin D angle does not.
Diabetic retinopathy
Observational data links lower 25(OH)D with more severe diabetic retinopathy in type 2 diabetes. Small trials suggest supplementation may slow progression, but well-powered evidence is limited. Glycaemic control, blood pressure control, and anti-VEGF therapy for proliferative disease remain the primary interventions.
Uveitis and other inflammatory eye disease
Cross-sectional studies find lower 25(OH)D in patients with anterior uveitis and keratoconjunctivitis. Given vitamin D's immunomodulatory role, correcting deficiency in inflammatory eye disease is reasonable adjunctive care.